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Photocatalysts

With a flux of 1000 W/m2, the solar energy incident on the earth's surface is sufficient to meet all human energy needs. One approach to harnessing this energy involves mimicking the successful photosynthetic reactions of plants and some bacteria where solar energy is used to split water into molecular hydrogen and oxygen fuels. Since the discovery of the first artificial water-splitting system in 1972, many inorganic materials have been identified as active catalysts for photochemical water-splitting often incorporating wide bandgap semiconductors (e.g. TiO2) that generate energetic electron-hole pairs upon the absorption of ultraviolet (UV) photons. The resulting conduction-band electrons and valence-band holes reduce and oxidize water to form H2 and O2, respectively. However, before widespread use of man-made photocatalysts is practical, their efficiencies must appreciably improve which requires:

  1. Improving light absorption in the visible where most of the solar radiation exists,
  2. Reducing oxidative instability, and
  3. Reducing competitive electron-hole recombination dynamics. These complications can be addressed with inorganic co-catalyst nanoparticles, which possess large surface to volume ratios, short charge transport pathways, and exhibit optical and chemical properties that can be manipulated through size, structure, and capping ligands.

 

References

  • CdS Trap Passivation Facilitates Photocatalytic Hydrogen Generation in CdSe/CdS Nanocrystals, Arthur Thibert, F. Andrew Frame, Erik Busby, Michael Holmes, Frank E. Osterloh, Delmar S. Larsen, submitted (2011).
  • Primary Photodynamics of Water Solubilized Two-Dimensional CdSe Nanoribbons, Arthur Thibert, F. Andrew Frame, Erik Busby, Delmar S. Larsen, in press (2011).
  • Evolution of physical and photocatalytic properties in the layered titanates A2Ti4O9 (A=K, H) and in nanosheets derived by chemical exfoliation"  Allen, Mark; Thibert, Arthur; Sabio, Erwin; Browning, Nigel;, Delmar S Larsen, Frank Osterloh, Chemistry of Materials 2010, 22 (3), 1220–1228 (2009). pdf
  • K4Nb6O17-derived Photocatalysts for Hydrogen Evolution from Water: nanoscrolls versus Nanosheets, Michael C. Sarahan, Elizabeth C. Carroll, Delmar S. Larsen, Nigel D. Browning, Frank E. Osterloh, J. Solid State Chem, 181 (7) 1681-1686 (2008). pdf
  • CdSe Nanoribbons as Photocatalysts for Hydrogen Evolution from Water, Andrew F. Frame; Elizabeth Carroll, Delmar S. Larsen, Michael Sarahan, Nigel Browning, Frank Osterloh, Chem. Commun. 2206-2208 (2008). pdf
  • Ultrafast Carrier Dynamics in Exfoliated and Functionalized Calcium Niobate Nanosheets in Water and Methanol, Elizabeth Carroll, Owen Compton, Dorte Madsen, Frank Osterloh, Delmar Larsen, Journal of Physical Chemistry C, 112, 2394-2403 (2008). pdf
  • Synthesis and Characterization of Manganese-Doped Silicon Nanoparticles: Bifunctional Paramagnetic-Optical Nanomaterial, Xiaoming Zhang, Marcin Brynda, R. David Britt, Elizabeth C. Carroll, Delmar S. Larsen, Angelique Y. Louie, and Susan M. Kauzlarich, J. AM. CHEM. SOC. 9 VOL. 129 (2007). pdf